Antennas for mobile communication and satellite broadcasting applications need to have the capability of changing the beam direction (referred to as “beam scanning” or “beam steering”). As antennas having such a capability (hereinafter referred to as “scanned antennas”), phased array antennas including antenna elements have been known in the art. However, the high cost of conventional phased array antennas has been an obstacle for their widespread application to consumer products. Particularly, the cost increases significantly when the number of antenna elements increases.
In view of this, scanned antennas have been proposed in the art that utilize the high dielectric anisotropy (birefringence) of liquid crystal materials (including nematic liquid crystals and polymer-dispersed liquid crystals) (Patent Document Nos. 1 to 4 and Non-Patent Document No. 1). The dielectric constant of a liquid crystal material has a frequency dispersion, and the dielectric constant in the microwave frequency band (which may be referred to as the “dielectric constant for microwaves”) will be particularly designated as “dielectric constant M(εM)” in the present specification.
Patent Document No. 3 and Non-Patent Document No. 1 state that an inexpensive scanned antenna can be realized by using technology for liquid crystal display devices (hereinafter referred to as “LCDs”).